BUCKWHEAT FAMILY 61 



18. Polygonum confertifldrum Nutt. Dense-flowered Knotweed. Fig. 1460. 



Polygonum Watsonii Small, Mem. Dept. Bot. Columbia Univ. 1: 138. pi. 56, as to description. 1895. 

 Polygonum conf ertiflorum Nutt. ex Piper, Contr. U.S. Nat. Herb. 11: 228. 1906. 

 Polygonum imbricatum var. Watsonii Small ex Jepson, Man. Fl. PI. Calif. 290'. 1925. 



Annual, slender, glabrous, or usually scurfy at the nodes, the stems erect, simple or usually 

 branched, 3-15 cm. high. Leaves narrowly linear-lanceolate, 1-3.5 cm. long; flowers in short 

 terminal bracted racemes ; floral bracts similar to the leaves but reduced, 5-10 mm. long, crowded 

 and imbricate with a narrow white margin ; flowers several to each bract ; calyx 2 mm. long, the 

 lobes oblong-ovate, about equal with green midrib and usually pinkish margins; stamens 3-5; 

 style 3-cleft to below the middle ; achene 3-angled, narrowly ovoid, prominently striate-granular, 

 dull black. 



Moist flats and banks, Arid Transition Zones; Douglas County, eastern Washington, to northern California, 

 east to Colorado; mainly east of the Cascades but occurring west of these in the Willamette Valley and Siskiyou 

 Mountains. Type locality: Columbia Plains. Collected by Nuttall. June-July. 



19. Polygonum Bolanderi Brewer. Bolander's Knotweed. Fig. 1461. 



Polygonum Bolanderi Brewer ex A. Gray, Proc. Amer. Acad. 8: 400. 1872. 



Stems much branched from a woody caudex and root, suffrutescent but slender and wiry, 

 erect. 2-6 dm. high. Leaves linear or linear-subulate, 3-15 mm. long, about 1 mm. or less wide, 

 euspidate, rather obscurely articulate at base, minutely punctate ; stipule-sheaths with the upper 

 hyaline portion conspicuously lacerate and on the ultimate branchlets almost concealing the 

 leaves ; flowers 1 or 2 in the axils, sessile, forming slender leaf y-bracted spikes ; calyx white or 

 rose-colored with a greenish midvein; stamens 8; style 3-parted to the base; achene 3-angled, 

 oblong-ovoid, 25 mm. long, chestnut brown, smooth and shining. 



Dry 



gravelly or rocky slopes Sonoran and Arid Transition Zones; North Coast Ranges, Humboldt County 

 to Napa County, also Sierra Nevada in Butte County, California. Type locality: very dry rocky hills east of 

 Napa Valley, California. June-Nov. 



20. Polygonum californicum Meisn. California Knotweed. Fig. 1462. 



Polygonum californicum Meisn. in DC. Prod. 14: 100. 1856. 

 Polygonum Greenei S. Wats. Proc. Amer. Acad. 14: 295. 1875. 

 Duravia calif ornica Greene, Leaflets Bot. Obs. 1: 23. 1904. 

 Duravia Greenei Greene, loc. cit. 



Annual, glabrous, the stems slender and wiry, erect, 7-20 cm. high, branched and flexuous or 

 nearly simple, the branches spreading or ascending. Leaves narrowly linear, 1-3 cm. long, sub- 

 ulate-tipped, 3-nerved, not articulate ; stipule-sheaths 3-4 mm. long, conspicuously lacerate into 

 subulate bristles ; flowers solitary in each axil, forming in early stages rather open spikes, but 

 late in season compact by shortening of internodes; calyx 2-2.5 mm. long; style 3-parted to the 

 base ; achene 3-angled, 2 mm. long, narrowly oblong-ovoid, dark brown, smooth and shining. 



Dry hillside often in clay soil, Upper Sonoran Zone; Klickitat County, Washington, and Josephine County, 

 Oregon, and in California North Coast Ranges and Sierra Nevada to San Francisco and Mariposa Counties. 

 Type locality: dry places, Sacramento Valley, California. Collected by Hartweg. May-Oct. P. Greenei is. 

 Wats, is the autumnal stage when the internodes become shorter. 



21. Polygonum Parryi Greene. Parry's Knotweed. Fig. 1463. 



Polygonum Parryi Greene, Bull. Torrey Club 8: 99. 1881. 



Annual, glabrous, much branched and compact, 2-5 cm. high, or sometimes more loosely 

 branched and up to 10 cm. high, leafy throughout. Leaves narrowly linear, 5-20 mm. long, 

 subulate-tipped, with a marginal nerve on either side paralleling the midrib, not articulate; 

 stipule-sheaths becoming extremely lacerate and concealing the flowers, these solitary in nearly 

 all the axils down to the base, sessile ; calyx 1 . 5 mm. long ; stamens 8 ; style very short, 3-parted 

 to the base; achene 3-angled, oblong-ovoid, 1.5 mm. long, chestnut brown, smooth and shining. 



In sandy soil, Arid Transition Zone; Falcon Valley, southern Washington, to the Sierra Nevada and Cuya- 

 maca Mountains, California. Type locality: Yosemite Valley, California. June. 



22. Polygonum Bidwelliae S. Wats. Bidwell's Knotweed. Fig. 1464. 



Polygonum Bidwelliae S. Wats. Proc. Amer. Acad. 14: 294. 1879. 



Annual, glabrous, except for inconspicuous scurf at the nodes, the stems erect, 3-12 cm. 

 high, divergently branched, the branches often as long as or longer than the stem. Leaves nar- 

 rowly linear, 5-20 mm. long, subulate-tipped, 3-nerved, not articulate; stipule-sheaths conspicu- 

 ous, 2-parted, oblong-ovate, 3-4 mm. long, sharply serrate at the apex, or the lower ones at length 

 somewhat lacerate; flowers solitary in the leaf axils, the upper internodes becoming shortened 

 and forming bracted spikes 1-3 cm. long ; calyx roseate, 2 mm. long, completely concealed by the 

 silvery scarious sheaths ; stamens 8 ; style 3-parted to the base, the branches divergent ; achenes 

 3-angled, scarcely 2 mm. long, oblong, dark brown, smooth or minutely granular at the apex 

 and on the angles. 



Volcanic outcrops, Upper Sonoran Zone; foothills of the Sierra Nevada, east of Chico, Butte County, Cali- 

 fornia. Type locality: near Chico, California. May-June. 



23. Polygonum viviparum L. Viviparous Knotweed or Snakeweed. Fig. 1465. 



Polygonum viviparum L. Sp. PI. 360. 1753. 



Bistorta vivipara S. F. Gray, Nat. Arr. Brit. PI. 2: 268. 1821. 



Perennial, with corm-like scaly rootstocks and simple slender erect stems, 10-25 cm. high. 



